hylafax - weak hostname and username validation

Patrice Fournier discovered a vulnerability in the authorisation
subsystem of hylafax, a flexible client/server fax system. A local or
remote user guessing the contents of the hosts.hfaxd database could
gain unauthorised access to the fax system.

Some installations of hylafax may actually utilise the weak hostname
and username validation for authorized uses. For example, hosts.hfaxd
entries that may be common are

  192.168.0
  username:uid:pass:adminpass
  user@host

After updating, these entries will need to be modified in order to
continue to function. Respectively, the correct entries should be

  192.168.0.[0-9]+
  username@:uid:pass:adminpass
  user@host

Unless such matching of “username” with “otherusername” and “host” with
“hostname” is desired, the proper form of these entries should include
the delimiter and markers like this

  @192.168.0.[0-9]+$
  ^username@:uid:pass:adminpass
  ^user@host$

For the stable distribution (woody) this problem has been fixed in
version 4.1.1-3.1.

For the unstable distribution (sid) this problem has been fixed in
version 4.2.1-1.

We recommend that you upgrade your hylafax packages.